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 Precambrian
stromatolite is the oldest of all fossils, and with much labor
(cutting and polishing), it is most beautiful. The banding that
commonly appears in stromatolite is a record of the growth patterns
of colonies of microorganisms, principally photosynthetic prokaryotes
(e.g, cyanobacteria). The colors that are often expressed are
the result of the interaction of biological and sedimentary processes,
together with subsequent chemistry and mineral exchange.
This stromatolite
is at once, ancient (Precambrian), beautiful, and unusually colored.
Coming from the Chocolay Group in an area know as the Chocolay
Hills located southeast of Ishpeming, Michigan, it dates to the
Lower Proterozoic, some 2.2 to 2.4 Billion years old. This stromatolitic
carbonate has been hand-polished to a mirror finish on one side
exhibits intricate banding and a spectrum of colors close to orange,
lavender, and various tans, among others - rather like butterscotch
in areas.
This particular
specimen is hefty at 5.3 pounds, and is part of a cross section
of an individual, large bacterial colony that had a unsymmetrical
spherical form called Girvanella. This form is diminishingly rare
within the formation. The piece has been sliced across its largest
face, and that face hand-polished to a glassine finish.
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